This application claims benefit and priority from the following application: Japanese Patent Application No. JP 2002-354913, filed Dec. 6, 2002, the contents of which is incorporated herein by reference.
1. Technical Field
The present invention relates to a method and system for distinguishing various load conditions and recording and correcting data related to an installation error, such that initialization processing to eliminate the influence on irradiation control caused by the installation error of vehicle height detecting means can be accurately carried out in an irradiating direction control apparatus of a lighting unit for a vehicle.
2. Related Art
In a related art apparatus for correcting and controlling the irradiating direction of a headlamp for a vehicle corresponding to a change in the attitude of the vehicle, there is a related art apparatus for automatically adjusting the irradiating direction of a headlamp to maintain the irradiating direction in a predetermined state when the inclination of a vehicle body is changed (i.e., an auto-leveling apparatus).
In a related art application to a headlamp system having a large light quantity and using a discharge lamp as a light source, glare in the direction of oncoming traffic can be prevented, thereby enhancing safety.
The following related art configurations are known structures of the apparatus.
(1) A related art configuration in which the attitude of a vehicle is recognized by a vehicle height detecting means (a vehicle height sensor) attached to front and rear parts of the vehicle. The control amount of the optical axis of irradiation of a lighting unit based on a change from a reference attitude (a variation in a pitch angle) is calculated to drive an optical component (a reflecting mirror), thereby stably maintaining an irradiating direction.
(2) A related art configuration in which the vehicle height value of one of the axle portions of the front and rear wheels of a vehicle is estimated and predicted from information detected by a vehicle height detecting means (a vehicle height sensor) provided in the other axle portion. A pitch angle is obtained to calculate the control amount of the optical axis of irradiation of a lighting unit based on a variation thereof, thereby driving an optical component (a reflecting mirror) to stably maintain an irradiating direction.
In configuration (2), only one vehicle height detecting means is used. For this reason, the configuration (2) is advantageous in terms of cost and required installation space for the vehicle height detecting means.
However, the related art has various problems and disadvantages. For example, but not by way of limitation, it is necessary to employ a technique for guessing a change in the pitch angle of a vehicle more accurately. For example, but not by way of limitation, in a related art method the number of passengers of the front seat of the vehicle is determined by using a detection signal sent from a seating sensor of a passenger seat and carrying out suitable control for a load state. Additional discussion of this related art is disclosed in published Japanese patent application nos. JP-A-10-226271, JP-A-10-230777, and JP-A-2001-80409, the contents of which are incorporated herein by reference.
In each configuration, when the vehicle height sensor is used, precision in control is adversely affected if variation is caused in an installation state. For example, but not by way of limitation, an initializing switch records an installation error based on a design value in the storage means (memory) of an apparatus by operating or setting the switch. In actual control, it is possible to eliminate the influence of the installation error of the vehicle height sensor by calculating the attitude of the vehicle through an operation from vehicle height data corrected by using data stored in the storage means for vehicle height detection data.
However, the foregoing related art has various problems and disadvantages. For example, but not by way of limitation, there is a problem in that the initialization processing is not always carried out under the condition that the load state of a vehicle is usually set to be constant.
For example, but not by way of limitation, the initialization processing is carried out in a state of 10 L (liter) of gasoline without a passenger, in the assembly line of an automobile manufacturer. On the other hand, when a dealer carries out the initialization processing in a market, the residual amount of the gasoline is not constant, even if there is no passenger. In other words, the initialization processing is carried out within a wide range, from a small amount less than 10 L to a full state.
When the initialization processing is carried out and the load condition of the vehicle is not constant, the precision is not guaranteed. For example, but not by way of limitation, the optical axis of a lighting unit is corrected in an erroneous direction when a control error is great. As a result, glare is caused.